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BTU
Open-cast lignite mines in Lower Lusatia provide unique insights into human-induced environmental changes in the Northern European Lowland and improve our understanding of Quaternary landscape dynamics. The excursion will focus on soils and sediments of Late Pleistocene and Holocene age that have been modified by land use since the Slavic Middle Ages. In the vicinity of the open-cast mine Jänschwalde and in the Tauer forest north of Cottbus characteristic remains of historical charcoal production, a ridge-and-furrow system and late Quaternary rubification in soils are presented.
Pedology and effects on vegetation at two medieval ridge and furrow sites in northeastern Germany
(2018)
Knowledge of the position of archaeological remains in the surface relief provides important basic information for archaeological survey design and interpretation. Geomorphological processes in (pre)history may have resulted in a modification of the local relief around archaeological sites, especially in areas that are prone to sediment erosion and relocation, such as sheet sand and dune landscapes. In this study, we reconstructed and analysed the palaeorelief of an archaeological excavation site in an inland dune area in southern Brandenburg, Germany. The remains of two Mesolithic sites were documented in the archaeological excavations and found to be associated with a buried soil horizon. To gather information on the relief of the buried soil surface, we used a combination of sedimentological and pedological profile descriptions along archaeological survey trenches and geophysical prospection with ground penetrating radar supplemented with microdrone photography and photogrammetry, global positioning system (GPS) surveys, and analysis of LiDAR-based elevation models. A digital elevation model of the buried surface was generated and analysed using a geographical information system (GIS). A comparison of the palaeosurface model with the recent surface elevation model shows that sand remobilization resulted in a considerable reshaping of the relief. Further, an analysis of the buried surface model shows that the relief position of the two archaeological sites in the study area was considerably more prominent in relation to the corresponding buried soil surface than in relation to the recent surface morphology. The results affirm the significance of Holocene sediment relocation for the local surface morphology and the importance of considering such relief modifications in archaeological surveys.
This study outlines the opportunities to reconstruct Holocene landscape dynamics in active opencast lignite mines in southern Brandenburg (Germany). Studies on extensive outcrops that address geomorphology, pedology and archaeology provide unique insights into human-induced environmental changes. Our approach uses a variety of traditional and cutting-edge techniques to characterize small-scale landforms (high-resolution DEMs by micro-drone and LiDAR), to analyze soils and substrate properties in the field (GPR, ERT, geomagnetics, Field Portable XRF and XRD) and to provide chronological information (OSL, 14C, tree-ring dating). This approach is combined with a GIS for data integration. We present the most recent results and review important findings from the last several years. Studies conducted in the opencast mines focus on soil development and Late
Quaternary geomorphodynamics and as well as past land use and the legacy of agriculture and woodland use.
Our results regarding the human-induced geomorphodynamics are similar to those in other regions in Central Europe, but we also observe regional differences caused by the local setting, e.g., intensification of soil erosion coinciding with the expansion of farming of cultivated lands in the Slavic Middle Ages. By analyzing LiDAR data the largest area of historical charcoal production in the Northern European Lowland (NEL) has been revealed. We are clearly only beginning to understand the massive dimensions of charcoal production in the region and the impact on late Holocene geomorphodynamics. The usage of new high-resolution imagery is essential to identify small-scale anthropogenic landforms hidden in the landscape. Future work will consist of developing and improving our integrative approach. However, comprehensive ground truth data provided by the archaeological prospections in the open-cast mines are an excellent basis for GIS-based analyses of high-resolution ALS data and geomorphological research.
In the forefield of the open-cast mine Jänschwalde (north of Cottbus, Germany), archaeological excavations have revealed one of the largest charcoal production fields described so far. As remains of the historic charcoal kilns, small mounds of sediment rich in charcoal fragments and ash cover the soil surface. We applied a combination of methods for mapping such kiln relicts across a range of scales, in order to analyze the spatial distribution of kiln sites and to improve the understanding of historic forest use systems. In archaeological excavations in the mine forefield, the geometry of kiln relicts could be studied in high detail. We used a microdrone to record high-resolution photographs of excavation sites for the
documentation of kiln site ground plans and other traces of historic land use. Based on airborne laser
scanning elevation models, kiln site mapping was extended to areas beyond the mine forefield. Manual
digitization from shaded relief maps was used for mapping kiln sites in further woodland areas surrounding an historic ironwork north of Cottbus. An automated mapping approach based on template matching was developed to detect charcoal production fields on a larger scale, and was applied for an area of about 1000 km2up to now.
In archaeological excavations, about 900 kiln sites have been documented on an approximately 17 km2 large area. Excavation documentations and aerial photographs show variations in the kiln site ground plans. By manual digitization from Shaded Relief Maps, more than 5000 kiln sites with diameters up to 29 m were detected in the 32 km2 area of the royal forest Jänschwalder Heide north of Cottbus. First results of mapping for larger areas indicate similar densities, but smaller diameters of kiln sites in other charcoal production fields; and show that charcoal production is a so far underestimated component of the land use history in many areas in the Northern European Lowlands.
Charcoal produced in kilns or hearths was an important source of energy in many regions of Europe and Northern America until the 19th century, and charcoal production in hearths is still common in many other regions of the world. The remains of charcoal hearths are therefore a widespread legacy of historic land use in forest areas. Soils on charcoal hearth sites are characterized by a technogenic layer rich in charcoal and ash on top of the soil profile, and by a pyrogenic modification of substrates below the former hearth.
The aims of our study are to examine how these alterations to the natural soil profiles affect the soil water regime
and other soil physical properties, and to assess the relevance of these effects on the landscape scale. We present
first results of a mapping of hearth site occurrence in forest areas in the state of Brandenburg, Germany, and of a
characterization of the infiltration behaviour on hearth sites as compared with undisturbed forest soils. Results of mapping small-scale relief features from LIDAR-based digital elevation models show that charcoal hearths occur in a high density in many large forest areas throughout Brandenburg. In the areas studied so far, up to almost 3% of the soil surface were found to be affected by the remains of historic hearths. First analyses of soil physical properties indicate differences in the infiltration characteristics of hearth site soils and undisturbed forest soils: Hood infiltrometer measurements show a very high spatial variability of hydraulic conductivity for hearth site soils, and water-drop-penetration-time tests reflect extremely high hydrophobicity of the technogenic layer on the sites. Results of dye tracer experiment show considerably strong preferential flow and therefore a higher spatial variability of soil wetness below the hearth remains. Overall, our first results therefore indicate that the legacy effects of historic charcoal production might significantly affect overall site conditions in forest areas with a high density of charcoal hearth remains.
Late Holocene biochar enrichment in soils ‐ implications of an anthropogenic legacy for ecosystems
(2017)
Relict charcoal hearths (RCH) are a widespread feature in forested areas in Europe and the USA.
Before the usage of hard coal, charcoal from RCHs was the main energy source and chemical reagent for the production of iron from ore. Depending on region and age, RCHs have diameters CAA 2019 305
Poster session up to 30 m, and due to their size and shape they are nowadays often identified by GIS-analysis of widely available LiDAR data. We study the architecture and soil stratigraphy of RCHs in several type regions in the USA and Germany where high densities of RCHs are known (Connecticut, New Hampshire, Pennsylvania and Brandenburg, Bavaria) and propose a morphological classification scheme. Whereas RCHs on flatland mostly have a circular shape which is often surrounded by an about half a meter-wide ditch, RCHs on slopes are mostly elliptical and often have a different architecture than on flatland sites. While the RCH platforms in flatland are only about 30 cm higher than the surrounding area, the platform of RCHs on slopes has often a height of up to one meter in downslope direction. Therefore, RCHs on slopes are much easier to identify during GIS mapping than RCHs on flatland. Remarkably the size, shape and architecture between our studied RCHs in the USA and Germany are often very similar which could indicate common roots of collier’s knowledge and technology that can be explained by immigration of European craftsmen to New England in the 18th and 19th century.
Objective To investigate long-term recovery of allocentric and egocentric spatial orientation as a sensitive marker for hippocampal and extrahippocampal network function in transient global amnesia (TGA).
Methods A group of 18 patients with TGA performed an established real-space navigation paradigm, requiring allo- and egocentric spatial orientation abilities, 3 days (postacute stage) and 3 months (follow-up) after symptom onset. Visual exploration behavior and navigation strategy were documented by a gaze-controlled, head-fixed camera. Allo- and egocentric spatial orientation performance was compared to that of 12 age-matched healthy controls. Navigation-induced brain activations were measured using [18F]-fluorodeoxyglucose-PET in a subgroup of 8 patients in the postacute stage and compared to those of the controls.
Results In the postacute stage, the patients navigated worse and had higher error rates than controls in allocentric (p = 0.002), but not in egocentric, route planning (p = 0.30), despite complete recovery of verbal (p = 0.58) and figural memory (p = 0.11). Until follow-up, allocentric navigation deficits improved, but higher error rates and reduced use of shortcuts persisted (p < 0.0001). Patients still exhibited relatively more fixations of unique landmarks during follow-up (p = 0.05). PET measurements during the postacute stage showed increased navigation-induced brain activations in the right hippocampus, bilateral retrosplenial, parietal, and mesiofrontal cortices, and cerebellar dentate nucleus in patients compared to controls (p < 0.005).
Conclusions Patients with TGA show selective and prolonged deficits of allocentric spatial orientation. Activations in right hippocampal and extrahippocampal hubs of the cerebral navigation network functionally substitute for the deficit in creating and updating the internal cognitive map in TGA.
Deciphering the drivers of tree growth is a central aim of dendroecology. In this context, soil conditions may play a crucial role, since they determine the availability of water and nutrients for trees. Yet, effects of systematically differing soil conditions on tree growth render a marginally studied topic. In this context, relict charcoal hearths (RCH) – a widespread legacy of anthropogenic charcoal production – render a valuable ‘natural’ experiment to study possible effects of artificially altered soil conditions on tree growth. We hypothesize, that the differing physico-chemical properties of RCH result in differing wood properties if compared to trees growing on unmodified soils. To test this hypothesis, we analyzed tree-growth, wood density, and wood elemental concentrations of Scots pine as well as physico-chemical soil properties. We applied a classic control-treatment design to compare RCH with unmodified soils. Our analyses identified significantly lower above-ground wood production but systematically higher wood elemental concentrations in RCH-trees compared to control trees. Since we could not identify treatment-specific growth patterns, we hypothesize the observed lower above-ground productivity of Scots pine to indicate an increased root-shoot ratio to compensate for a potentially lower plant water availability on RCH-sites. The observed higher wood elemental concentrations likely reflect higher soil elemental concentrations of Fe, Ca, K, and Mn in RCH soils. In conclusion, our study highlights diverse effects of RCH on tree growth and wood properties and strengthens the value of dendro-chemistry to use the tree-ring archive as proxy for soil conditions within a dendro-ecological context.
Historic charcoal hearth remains provide a unique archive of the long term interaction between biochar, soil development and plant growth. Charcoal as raw material was crucial for production of iron in iron works and hence numerous charcoal hearths can be found in the forests near historic iron works in Europe as well as the Eastern United States. Charcoal hearths are round to elliptical forms often around 10 m in diameter, and consist of several decimeter thick layers that contain charcoal fragments, ash, and burnt soil. We studied the soil chemistry of 24 charcoal hearths and compared them to the surrounding ‘natural’ soils in the northern Appalachians of northwestern Connecticut. The thickness of the topsoils on the charcoal hearths and their carbon content are remarkably higher than in the surrounding topsoils. The presence of residual products from charcoal production classifies the soils as Anthropic Udorthents (US Soil Taxonomy) or Spolic Technosols (Humic) according to the World Reference Base for Soil Resources. The widespread occurrence of charcoal hearth remains and their high spatial density in different ecosystems underlines their importance for further pedological research.
Historical charcoal production can have significant effects on soil properties. We studied soils at former charcoal production sites (relict charcoal hearths, RCHs) and compared these soils with undisturbed soil next to the charcoal hearths and four typical soils on similar parent material located at distances between 10 and 70 km from the RCHs. In a landscape typical of the northern German lowland, we found Podsolige Braunerde [WRB: Brunic Arenosols (Protospodic)] outside of the RCHs and soils with a clearly different stratigraphy within the RCHs. The main feature of the soils at both of the studied RCHs is a heterogeneous, charcoal-bearing deposit that is ~30 cm thick. No indications of translocation or mineral transformation processes, which form distinct soil horizons after the deposition of anthropogenic material on the RCHs, are present. Except for the differences in color and total carbon content, the soil chemistry of the RCHs hardly differs from that of the soil outside of the charcoal hearth sites. The soil colors and magnetic susceptibility values strongly suggest that the RCH substrates and the underlying topsoil were affected by thermally induced transformation of iron (hydr-)oxides. Although the charring procedure normally requires ~2 weeks, the heating effect only reaches to a maximum depth of 8 cm into the buried soil below the charcoal hearths. The presence of reddish soil and an abrupt increase in magnetic susceptibility in the upper 2 cm of the soil below the charcoal hearths indicate the heat-induced transformation of iron (hydr-)oxides into maghemite. Brighter soil color and an increase in soil organic matter (SOM) in the lower parts of the buried topsoil demonstrate the combustion of SOM up to 5 cm depth below the RCH. According to the German Guidelines for Soil Mapping, the soils in the RCHs are classified as Regosols above Braunerde [WRB: Spolic Technosols (Arenic)]. However, because the anthropogenic features of these soil sediments are disregarded in the German Guidelines for Soil Mapping, we suggest adapting the “M” horizon to permit a jM horizon. Thus, the soils in the RCHs could be classified as Kolluviale Braunerde.
Relict charcoal hearths (RCHs) are sites of former charcoal production that are an increasingly well documented anthropogenic feature in forests of the temperate climate zone. However, the type and extent of a possible legacy effect from RCHs on soil physical and chemical properties is still largely unknown. In the Litchfield Hills in west Connecticut, RCH sites are located mainly on slopes and therefore differ in their architecture from lowland sites found in Europe. One of the striking characteristics of a RCH site regardless of its architecture is the enrichment of the soil with charcoal in varying particle sizes. In this study, we use chemical digestion coupled with a PLSR-model to quantify organic carbon and pyrogenic carbon in RCH substrate by MIR-DRIFT measurements. Furthermore, we analyse the quality of carbon compounds by MIR-DRIFT measurements on multiple grain size fractions to assess the post-burn enrichment of soil organic matter. Preliminary results show a markedly increase in organic and pyrogenic carbon in RCH substrates in relation to the natural forest soil. Also, our first results suggest that the enrichment of organic carbon is favoured on RCHsites. However, the causality between the enrichment of soil organic matter and site features remains open. Experiments using chemical extraction techniques on our samples hint at an increase of labile organic compounds and/or microbial biomass. This legacy effect of RCHs is however evident and further studies need to focus on how to address them.
Do small landforms have large effects? A review on the legacies of pre-industrial charcoal burning
(2022)
Relict charcoal hearths (RCHs) are small, anthropogenic landforms resulting from past charcoal burning and reaching significant land coverage in pre-industrial mining areas. We review three coupled legacies linked by RCH development: (i) a landscape-scale geomorphic effect, (ii) a unique soil fingerprint, and (iii) an evolving novel ecosystem. The history and technique of charcoal production are described to clarify legacy effects. Applying a recently presented morpho-genetic catalogue is useful for classified mapping of RCH findings. The RCH numbers and calculated RCH densities per study region vary greatly and impose uncertainties due to insufficient methods causing over- or underestimations. Areas with high RCH densities between 50 and 500 RCH/km2 seem reasonable. Machine learning-based remote sensing techniques are promising approaches with which to better assess the full scale of charcoal burning legacies. RCH soil properties feature dark charcoal-rich technogenic substrate layers classified as Auh horizons according to the World Reference Base with significantly increased C contents. These Auh horizons can also exhibit specific physical and chemical properties, such as relatively low bulk density, high porosity, high plant available water content, low thermal conductivity and differences in cation exchange capacity or nutrient status. However, relevant studies are rare, and thus, the effects may differ by study region. Regarding vegetation, there seem to be four main effects: changes in forest structure, species composition, recruitment pattern and productivity. The number of studies on this issue is, however, also very limited. Even fewer studies have examined the soil fauna in RCHs; thus, the reported effects cannot be used to draw general conclusions. Notably, RCH research has made considerable progress in the last five years, especially in the Light Detection and Ranging-based mapping of these small landforms and identification of RCH-specific soil properties, but ecological legacies are not well understood; thus, more interdisciplinary and integrative studies are needed.
Seit 2010 untersucht eine interdisziplinäre Forschergruppe der BTU, des BLDAM und des LBGR die Landnutzungsgeschichte sowie die natürliche und anthropogen induzierte Landschaftsentwicklung in der Niederlausitz, Brandenburg. Systematische archäologische Grabungen des BLDAM im Vorfeld der laufenden Tagebaue sind eine wichtige Grundlage für geopedologische Untersuchungen. Die Arbeiten hatten zunächst ihren räumlichen Schwerpunkt in den Braunkohletagebauen nordöstlich von Cottbus (Tgb. Cottbus Nord, Tgb. Jänschwalde) und wurden dann ausgedehnt auf weitere Forstflächen nördlich von Peitz. Wir geben einen Überblick über die wichtigsten Erkenntnisse der letzten Jahre, präsentieren aktuelle Ergebnisse und zeigen zukünftige Forschungsfelder auf.
Im Tagebau Jänschwalde sind zwischenzeitlich mehr als 1000 Relikte von Holzkohlmeilern (HKM) als Zeugen einer intensiven historischen Holznutzung archäologisch dokumentiert. Mit Stand Januar 2016 liegen Dendroalter von 64 HKM vor. Die Alter schwanken zwischen dem ausgehenden 16. Jahrhundert und der Mitte des 19. Jahrhunderts, was in etwa dem Betriebszeitraum des Hüttenwerks in Peitz entspricht. Die Mehrzahl der Meiler datiert auf den Beginn des 18. Jahrhunderts. Weitere Hinterlassenschaften der historischen Landnutzung sind u.a. Wölbäcker und begrabene Ackerböden. Fossile Böden und ehemalige Landoberflächen sind stellenweise mit äolischen Sedimenten überdeckt. 14C- und OSL-Datierungen an diesen Böden und Sedimenten lassen auf eine Intensivierung der äolischen Aktivität zur slawischen Zeit und im Deutschen Mittelalter schließen. Einige Relikte von HKM sind mit Sand überweht worden, und an einer Stelle konnte das Alter dieser äolischen Sedimentation mittels Dendrodatierung des begrabenen Meilers auf1850 oder jünger bestimmt werden. Allerdings stellt dies die Ausnahme dar. Der weitaus größere Teil der HKM-Relikte liegt direkt an der Oberfläche und ist nicht begraben, was auf eine sehr geringe Winderosion in der Neuzeit schließen lässt. Seit 2015 konnte im Rahmen des DFG-Projekts „Räumliche und zeitliche Dimension der historischen Köhlerei im Tauerschen Forst (Niederlausitz, Brandenburg). Ein Beitrag zur Kulturlandschaftsentwicklung des Norddeutschen Tieflands“ (Az RA 1129/3-1; RA 931/6-1) ein weiteres Gebiet mit hoher HKM-Dichte untersucht werden. Erste Auswertungen der LiDAR-Daten ergeben eine Anzahl von 4449 ehemaligen Meilerstandorten im Tauerschen Forst. 26 Meilerstellen sind beprobt, die Dendroalter hierzu sind in Bearbeitung. Ebenfalls in jüngerer Zeit fanden Untersuchungen zur Verbreitung von HKM-Relikten für das gesamte Land Brandenburg statt. Mit Hilfe eines binären Modells wurden Gebiete mit hoher Wahrscheinlichkeit von HKM-Standorten detektiert. Im Rahmen des im November 2016 beginnenden DFG-Projekts „Die historische Köhlerei in Brandenburg - Analyse der räumlichen Dimension und der Effekte auf bodenhydraulische Eigenschaften“ (SCHN 1349/1-1) sollen nun neben der Verbreitung der historischen Köhlerei auch bodenrelevante Auswirkungen beschrieben und bewertet werden.
Various sources provide information about land use history and landscape transformation. For a variety of reasons, the quality of information differs and is often discontinuous or incomplete. In this interdisciplinary study we take advantage of comprehensive archaeological data gathered by large-scale excavations that were necessary because of opencast lignite mining in Lusatia, Brandenburg, Germany. By using a GIS we integrate these archaeological findings with results from archival and literature studies, from historical maps, from landforms and soils as well as from analyses of shaded-relief maps derived from up-to-date LiDAR data. The long-term aim is to develop a palaeoenvironmental model and thus to reconstruct landscape changes caused by human activities. The focus of the study is the Peitz ironwork in SE Brandenburg, which was a large consumer of commodities for about 300 years. During the time it operated, extensive transformations are supposed to have affected the landscape in the vicinity because of wood consumption and especially charcoal production. Digital datasets about forested areas for different timespans reconstructed from historical maps were made available. In combination with dendrochronological dating of charred trees, the spatiotemporal dimension of charcoal kilns was determined. Also, sites of former bog iron ore mining could be identified. Moreover, the different sources contain further information about other forms of land uses such as agriculture, pastoralism and even viticulture. In conclusion we can highlight that the mosaic of past land use systems is different from the modern structure but that major changes in the forests have been retained.
Recent findings of several thousand relict charcoal hearths (RCHs) in the Tauer Forest (Brandenburg, Germany) raise questions about the legacy effects of historical charcoal production on soil properties. RCH sites are characterized by the admixture of charcoal fragments to the natural forest soil, constituting an anthropogenic addition of carbon. Dendrochronological dating of large charcoal pieces has identified RCH ages ranging from 1709 AD to 1823 AD for a subarea in the Tauer Forest, which allows for assessing century old effects of charcoal application on forest soils. We measured the geometry and soil organic matter (SOM) content of 20 RCH sites in a selected part of the forest. The results provide a basis for estimating RCH SOM stocks on a 40-ha forest plot with 120 RCH sites. We also assessed the accuracy of RCH mapping based on digital elevation models (DEMs) with results from a ground survey. Over 50 % of sites were not detected by the DEM-based mapping. In the range of statistical uncertainties, RCHs add between 18 % and 32 % of SOM to the stock of the natural forest soil in the study area. This equals an additional 4.9 – 8.9 Mg of carbon per hectare of forest soil. These substantial amounts of SOM are so far not recognized by any survey or forest soil SOM inventories. Considering recent studies, which uncovered tens- and hundreds- of thousands of RCHs throughout Europe and the USA, we conclude that further knowledge of RCH SOM is important for quantifying anthropogenic SOM stocks on a global scale.
Historical charcoal production has long been an unconsidered type of forest utilization in lowland areas. The archaeological discovery of a large charcoal burning area in the forefield of the active opencast lignite mine J€anschwalde in SE Brandenburg (North German Lowlands) has highlighted the need for multidisciplinary research in the study of the dimensions of historical charcoal burning. The charcoal produced in our study area, the former royal forest district Tauer, provided energy for the nearby Peitz ironworks during its operation from the mid-16th to the mid-19th century. Here, we aimed to record the amount, size and distribution of relict charcoal hearths (RCHs) to examine their context with respect to the ironworks and to better understand the potential impacts on late Quaternary landscape change. The applied methods combined archaeological research with shaded-relief mapping of RCHs. To evaluate the detection success of RCHs in the shaded-relief maps (SRMs), we compared the results with the results from specific archaeological surveys and conventional forest site mapping. Furthermore, we analyzed our dataset with descriptive, comparable and spatial statistics. Additionally, dendrochronological dating of charcoal fragments from selected RCHs was used to investigate the temporal relationships among the RCHs. Approximately 6000 circular RCHs were manually digitally identified in the SRMs of the 109-km2 evaluable area. However, ground truthing showed that the shaded-relief maps could not completely capture all RCHs in our study area due to local conditions. At the regional scale, two focus areas with high RCH site densities were found. Statistical analysis revealed that the diameters of the RCHs range widely from 4 to 30.5 m. Spatial statistics were applied to the RCH diameters to aggregate areas with larger or smaller RCHs. At the small scale, no systematic arrangement of RCHs was obvious in the SRMs. Dendrochronological dating of selected RCHs lying close together could not detect significant spatiotemporal relationships or patterns. The dating results also showed that some areas have been preferentially used for charcoal production for over 300 years. Due to the homogeneity of the physiogeographical location factors, we assume that these factors are not superficially responsible for site selection. Instead, economic location factors and contemporary regulations are more likely responsible for the distribution of RCHs.
An initiative for a morphologic‐genetic catalog of relict charcoal hearths from Central Europe
(2020)
Human land use often leads to distinct modifications of soils within small, clearly delimited areas. Legacy effects of past land use are also abundant in recent forest areas, but are hardly considered in ecosystem assessment and soil mapping. The soils on relict charcoal hearths (RCHs) are a widespread example for such land use legacy soils in forests. Soils on RCHs differ clearly from surrounding forest soils in their stratigraphy and properties, and are most prominently characterized by a technogenic substrate layer with high contents of charcoal and thus soil organic matter (SOM). Although RCH soils can clearly contribute to the SOM stocks of forest soils, their relevance on the landscape scale has hardly been quantified. In this paper we analyze and discuss the distribution and effects of RCH soils across scales for forests in the state of Brandenburg, Germany, with a focus on SOM stocks. Our analysis is based on a large-scale mapping of RCHs from digital elevation models (DEMs), combined with a linear regression model of SOM stocks in RCH soils. The spatial distribution of RCH soils in the study region has a scale dependent heterogeneity. The large-scale variation in site densities is related to the concentration of charcoal production to specific forest areas while the small-scale variation is related to the irregular distribution of single RCHs within the charcoal production fields. Up to 1.5 % of the surface are covered by RCH soils in the forest areas within the study region. The results also show that RCHs can significantly contribute to the SOM stocks of forests, even where they cover only a small fraction of the soil surface, with up to 18 % additional SOM for forest areas. Because of the heterogeneous distribution of RCHs, the SOM stock additions depend on the scale of observation. Our results suggest that RCH SOM additions can be overestimated when sites in small areas (< 1 km²) are analyzed; and that characteristic spatial concentration patterns of RCHs are even observable when values are aggregated to large areas (25 km² and more). Aggregating effects to irregularly-sized forest administrative units resulted in maps that well represent the spatial distribution of RCH soils and SOM. The study highlights that considering land use legacy effects can be relevant for the results of soil mapping and inventories; and that prospecting and mapping land use legacies from DEMs can contribute to improving such approaches.
Charcoal-rich Technosols on century-old relict charcoal hearths (RCHs) are the subject of ongoing research regarding potential legacy effects that result from historic charcoal production and subsequent charcoal amendments on forest soil properties and forest ecosystems today. RCHs consist mostly of Auh horizons that are substantially enriched in soil organic carbon (SOC), of which the largest part seems to be of pyrogenic origin (PyC). However, the reported range of SOC and PyC contents in RCH soil also suggests that they are enriched in nonpyrogenic SOC. RCH soils are discussed as potential benchmarks for the long-term influence of biochar amendment and the post-wildfire influences on soil properties. In this study, we utilised a large soil sample dataset (n = 1245) from 52 RCH sites in north-western Connecticut, USA, to quantify SOC contents by total element analysis. The contents of condensed highly aromatic carbon as a proxy for black carbon (BC) were predicted by using a modified benzene polycarboxylated acid (BPCA) marker method in combination with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy-based partial least square regression (r2 = 0.89). A high vertical spatial sampling resolution allowed the identification of soil organic matter (SOM) enrichment and translocation processes. The results show an average 75% and 1862% increase in TOC and BPCA-derived carbon, respectively, for technogenic Auh horizons compared to reference soils. In addition to an increase in aromatic properties, increased carboxylic properties of the RCH SOC suggest self-humification effects of degrading charcoal and thereby the continuing formation of leachable aromatic carbon compounds, which could have effects on pedogenic processes in buried soils. Indeed, we show BPCA-derived carbon concentrations in intermediate technogenic Cu horizons and buried top/subsoils that suggest vertical translocation of highly aromatic carbon originating in RCH Auh horizons. Topmost Auh horizons showed a gradual decrease in total organic carbon (TOC) contents with increasing depth, suggesting accumulation of recent, non-pyrogenic SOM. Lower aliphatic absorptions in RCH soil spectra suggest different SOM turnover dynamics compared to reference soils. Furthermore, studied RCH soils featured additional TOC enrichment, which cannot be fully explained now.
In Central Europe, Late Quaternary landscapes experienced multiple phases of geomorphologic activity. In this study,we used a combined geomorphological, pedological, sedimentological and palynological approach to characterize landscape development after the Last Glacial Maximum (LGM) near Lake Wygonin in Northern Poland. The pedostratigraphical findings from soil pits and drillings were extrapolated using ground-penetrating radar (GPR) and electric resistivity tomography (ERT). During the Pomeranian phase, glacial and fluvioglacial processes dominated the landscape near Lake Wygonin. At the end of the glacial period, periglacial processes became relevant and caused the formation of ventifacts and coversands containing coated sand grains. At approximately 15,290–14,800 cal yr BP, a small pond formed in a kettle hole (profile BWI2). The lacustrine sediments lack eolian sand components and therefore indicate the decline of eolian processes during that time. The increase of Juniperus and rock-rose (Helianthemum) in the pollen diagram is a prominent marker of the Younger Dryas. At the end of the Younger Dryas, a partial reshaping of the landscape is indicated by abundant charcoal fragments in disturbed lake sediments. No geomorphologic activity since the beginning of the Holocene is documented in the terrestrial and wetland archives. The anthropogenic impact is reflected in the pollen diagram by the occurrence of rye pollen grains (Secale cereale) and translocated soil sediments dated to 1560–1410 cal yr BP, proving agricultural use of the immediate vicinity. With the onset of land use, gully incision and the accumulation of colluvial fans reshaped the landscape locally. Since 540–460 cal yr BP, further gully incision in the steep forest tracks has been associated with the intensification of forestry. Outside of the gully catchments, the weakly podzolized Rubic Brunic Arenosols show no features of Holocene soil erosion.